In a telecommunication system, it is often necessary to measure the Signal to Noise Ratio (“SNR”) of a speech signal. SNR is a measure that quantifies the level of background noise in a speech signal and is related to the perceptual speech quality. This might be needed, for example, for assuring quality of service in network gateways, or to determine whether a speech signal is suitable or not for automatic speech recognition, or to determine whether noise reduction should or should not be applied in the network. In telephone networks, speech is transmitted in a coded form such as adaptive multi-rate (“AMR”), global system for Mobile Communication (“GSM”), etc. In order to measure the SNR it is normally necessary to decode the signal first to linear pulse code modulation (“PCM”) and then apply a non-intrusive (single-ended) SNR estimation algorithm. The decoding task adds additional computation complexity that, when deployed on networks carrying high volume traffic, becomes itself a significant computational overhead.